The invention relates to high pressure roller presses for interparticle crushing and more particularly to an improved bearing support for one of the rolls accommodating the high forces in the nip and permitting changes in the nip width from one end of the nip to the other.
In the development of interparticle crushing as disclosed in the Schoenert U.S. Pat. No. 4,357,287, while attempts are made to obtain uniform particle draw-in along the length of the nip between two opposed rolls, unequal draw-in can occur. For the high nip forces which are necessary for interparticle crushing, it is necessary to permit relative movement between the rolls and further to permit the nip width to change from one end to the other while maintaining the very high nip pressure. Nip pressures of 500 kg per square centimeter of nip length are employed in accordance with the teaching of the foregoing Schoenert patent. To attain these high nip pressures and yet accommodate movement of the bearings, creates unique problems not encountered in ordinary roller presses.
In accordance with the structural requirements, the rollers are seated in bearings having at one end an axially fixed nonmovable bearing and at the other end an axially yieldable or resilient movable bearing. The bearings are further guided accommodating movement in the plane parallel to the roller axis. The rollers are resiliently pressed toward each other with pressing power provided by force elements.
German Published Application 28 31 249 discloses an apparatus for protecting the bearings in roller mills against overload. In that patent, one bearing housing of each roller is arranged resilient in an axial direction in the machine frame. Changes in length and the increased axial shearing forces of the bearings involved that occur due to heating during operation can be avoided in this way. Swivel joint roller bearings are provided for supporting the rollers.
A publication of the Swedish Ball Bearing Factories SKF having the title "Einsatz von Pendelrollenlagern bei Rollenpressen" is relevant for this structure. The bearings are usually designed such that the outer ring of the bearing can move in an axial direction in the bearing housing at the movable bearing side with thermal change in length or the oblique change in position of the press rolls. This, however, only occurs under pressing power. As a consequence of the actual forces thereby occurring, bearing load occurs that reduces the available useful life of the bearing up to approximately 50%.